//download.js v4.21, by dandavis; 2008-2018. [MIT] see http://danml.com/download.html for tests/usage
// v1 landed a FF+Chrome compatible way of downloading strings to local un-named files, upgraded to use a hidden frame and optional mime
// v2 added named files via a[download], msSaveBlob, IE (10+) support, and window.URL support for larger+faster saves than dataURLs
// v3 added dataURL and Blob Input, bind-toggle arity, and legacy dataURL fallback was improved with force-download mime and base64 support. 3.1 improved safari handling.
// v4 adds AMD/UMD, commonJS, and plain browser support
// v4.1 adds url download capability via solo URL argument (same domain/CORS only)
// v4.2 adds semantic variable names, long (over 2MB) dataURL support, and hidden by default temp anchors
// https://github.com/rndme/download

export function download(data, strFileName, strMimeType) {
    var self = window, // this script is only for browsers anyway...
        defaultMime = 'application/octet-stream', // this default mime also triggers iframe downloads
        mimeType = strMimeType || defaultMime,
        payload = data,
        url = !strFileName && !strMimeType && payload,
        anchor = document.createElement('a'),
        toString = function (a) {
            return String(a)
        },
        myBlob = self.Blob || self.MozBlob || self.WebKitBlob || toString,
        fileName = strFileName || 'download',
        blob,
        reader
    myBlob = myBlob.call ? myBlob.bind(self) : Blob

    if (String(this) === 'true') {
        //reverse arguments, allowing download.bind(true, "text/xml", "export.xml") to act as a callback
        payload = [payload, mimeType]
        mimeType = payload[0]
        payload = payload[1]
    }

    if (url && url.length < 2048) {
        // if no filename and no mime, assume a url was passed as the only argument
        fileName = url.split('/').pop().split('?')[0]
        anchor.href = url // assign href prop to temp anchor
        if (anchor.href.indexOf(url) !== -1) {
            // if the browser determines that it's a potentially valid url path:
            var ajax = new XMLHttpRequest()
            ajax.open('GET', url, true)
            ajax.responseType = 'blob'
            ajax.onload = function (e) {
                download(e.target.response, fileName, defaultMime)
            }
            setTimeout(function () {
                ajax.send()
            }, 0) // allows setting custom ajax headers using the return:
            return ajax
        } // end if valid url?
    } // end if url?

    //go ahead and download dataURLs right away
    if (/^data:([\w+-]+\/[\w+.-]+)?[,;]/.test(payload)) {
        if (payload.length > 1024 * 1024 * 1.999 && myBlob !== toString) {
            payload = dataUrlToBlob(payload)
            mimeType = payload.type || defaultMime
        } else {
            return navigator.msSaveBlob // IE10 can't do a[download], only Blobs:
                ? navigator.msSaveBlob(dataUrlToBlob(payload), fileName)
                : saver(payload) // everyone else can save dataURLs un-processed
        }
    } else {
        //not data url, is it a string with special needs?
        if (/([\x80-\xff])/.test(payload)) {
            var i = 0,
                tempUiArr = new Uint8Array(payload.length),
                mx = tempUiArr.length
            for (i; i < mx; ++i) tempUiArr[i] = payload.charCodeAt(i)
            payload = new myBlob([tempUiArr], { type: mimeType })
        }
    }
    blob = payload instanceof myBlob ? payload : new myBlob([payload], { type: mimeType })

    function dataUrlToBlob(strUrl) {
        var parts = strUrl.split(/[:;,]/),
            type = parts[1],
            indexDecoder = strUrl.indexOf('charset') > 0 ? 3 : 2,
            decoder = parts[indexDecoder] == 'base64' ? atob : decodeURIComponent,
            binData = decoder(parts.pop()),
            mx = binData.length,
            i = 0,
            uiArr = new Uint8Array(mx)

        for (i; i < mx; ++i) uiArr[i] = binData.charCodeAt(i)

        return new myBlob([uiArr], { type: type })
    }

    function saver(url, winMode) {
        if ('download' in anchor) {
            //html5 A[download]
            anchor.href = url
            anchor.setAttribute('download', fileName)
            anchor.className = 'download-js-link'
            anchor.innerHTML = 'downloading...'
            anchor.style.display = 'none'
            anchor.addEventListener('click', function (e) {
                e.stopPropagation()
                this.removeEventListener('click', arguments.callee)
            })
            document.body.appendChild(anchor)
            setTimeout(function () {
                anchor.click()
                document.body.removeChild(anchor)
                if (winMode === true) {
                    setTimeout(function () {
                        self.URL.revokeObjectURL(anchor.href)
                    }, 250)
                }
            }, 66)
            return true
        }

        // handle non-a[download] safari as best we can:
        if (/(Version)\/(\d+)\.(\d+)(?:\.(\d+))?.*Safari\//.test(navigator.userAgent)) {
            if (/^data:/.test(url)) url = 'data:' + url.replace(/^data:([\w\/\-\+]+)/, defaultMime)
            if (!window.open(url)) {
                // popup blocked, offer direct download:
                if (confirm('Displaying New Document\n\nUse Save As... to download, then click back to return to this page.')) {
                    location.href = url
                }
            }
            return true
        }

        //do iframe dataURL download (old ch+FF):
        var f = document.createElement('iframe')
        document.body.appendChild(f)

        if (!winMode && /^data:/.test(url)) {
            // force a mime that will download:
            url = 'data:' + url.replace(/^data:([\w\/\-\+]+)/, defaultMime)
        }
        f.src = url
        setTimeout(function () {
            document.body.removeChild(f)
        }, 333)
    } //end saver

    if (navigator.msSaveBlob) {
        // IE10+ : (has Blob, but not a[download] or URL)
        return navigator.msSaveBlob(blob, fileName)
    }

    if (self.URL) {
        // simple fast and modern way using Blob and URL:
        saver(self.URL.createObjectURL(blob), true)
    } else {
        // handle non-Blob()+non-URL browsers:
        if (typeof blob === 'string' || blob.constructor === toString) {
            try {
                return saver('data:' + mimeType + ';base64,' + self.btoa(blob))
            } catch (y) {
                return saver('data:' + mimeType + ',' + encodeURIComponent(blob))
            }
        }

        // Blob but not URL support:
        reader = new FileReader()
        reader.onload = function (e) {
            saver(this.result)
        }
        reader.readAsDataURL(blob)
    }
    return true
} /* end download() */
